Photo Diodes Having a Conductive Plug Contact to a Buried Layer and Methods of Manufacturing the Same

Abstract

Methods of manufacturing a photo diode include sequentially forming a buried layer of a first conductivity type, a first epitaxial layer of the first conductivity type, and a second epitaxial layer of a second conductivity type on a substrate. The second and first epitaxial layers are etched to form a trench that exposes a portion of the buried layer. A conductive plug of the first conductivity type is formed in the trench. A first electrode is formed on an upper surface of the second epitaxial layer. A second electrode may be formed to contact an upper surface of the conductive plug. Photodiodes having a conductive plug contact to a buried layer are also provided.

1 . A photo diode comprising:
 a buried layer of a first conductivity type on a substrate;   a first layer of the first conductivity type on the buried layer;   a second layer of a second conductivity type on the first layer;   a conductive plug that extends through the second and first layers and contacts the buried layer; and   a first electrode on an upper surface of the second layer.   
     
     
         2 . The photo diode of  claim 1 , further comprising a second electrode on an upper surface of the conductive plug. 
     
     
         3 . The photo diode of  claim 1 , wherein the conductive plug comprises Boro-Silicate-Glass, Phospho-Silicate-Glass or doped polysilicon. 
     
     
         4 . The photo diode of  claim 1 , wherein a dopant density of the conductive plug is from about 1E20 to about 1E21 ions/cm 3 . 
     
     
         5 . The photo diode of  claim 1 , wherein the upper surface of the conductive plug is flat. 
     
     
         6 . The photo diode of  claim 1 , further comprising a region of higher concentration of dopants of the second conductivity type disposed between the first electrode and the second layer. 
     
     
         7 . The photo diode of  claim 6 , wherein the conductive plug comprises a plurality of conducive plugs that extend through the second and first layers and contact the buried layer, the first electrode comprises a plurality of first electrodes, the second electrode comprises a plurality of second electrodes, the photo diode further comprising:
 regions of higher concentration of dopants of the second conductivity type disposed between the first electrodes and the second layer; and   a region of the first conductivity type disposed in the second layer between the regions of higher concentration of dopants of the second conductivity type.   
     
     
         8 . The photo diode of  claim 1 , further comprising:
 an inter-metal dielectric which covers the first and second electrodes;   a light-shielding layer on the inter-metal dielectric to define a photosensitive section; and   a conformal anti-reflection coating layer in the photosensitive section.